Multi-element LED lamp package

ABSTRACT

A light emitting diode device (e.g., LED package) may include at least two light emitting devices that can be switched independently of one another and thus may be useful in vehicular lighting applications, for example low and high beam headlights. A LED device may include a first LED die and at least one additional LED die disposed at different positions within a common reflector cup or relative to a common lens. Multiple LED sub-assemblies may be mounted to a common lead frame along non-coincident principal axes. Methods for varying intensity or color from multi-LED lamps are further provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 12/895,108filed on Sep. 30, 2010 and subsequently issued as U.S. Pat. No.8,324,635, which is a divisional of U.S. patent application Ser. No.11/416,804 filed on May 3, 2006 and subsequently issued as U.S. Pat. No.7,829,899. The disclosures of the foregoing applications and patents arehereby incorporated by reference herein in their respective entireties,for all purposes, and the priority of such applications is herebyclaimed under the provisions of 35 U.S.C. §120.

FIELD OF THE INVENTION

Certain embodiments of the invention relates to a light source assemblyincluding a plurality of LED elements that can be switched independentlyof one another, said light source assembly being useful for variousapplications including vehicular headlights and running lights.

BACKGROUND

In the field of exterior and interior illumination of motor vehicles,light-emitting diodes (LEDs) are being increasingly used instead ofconventional incandescent bulbs, particularly for tail lights and brakelights, since LEDs have a longer service life, better efficiency inconverting electrical energy into radiation energy in the visiblespectral range, lower thermal emission characteristics, and reducedspace requirements.

The practical advantages of utilizing LED lamps instead of incandescentbulbs are many. The operational lifetime (in this case, defined ascontinuous illumination service) of a LED is on the order of ten yearsor over 50,000 hours, whereas incandescent bulbs often burn out afterabout 2,000 hours of service. Additionally, LED lamps are considerablymore robust. When exposed to mechanical shocks or stresses, chemicalstresses (e.g., such as may be caused by cleaning chemicals or roadsalt), or the presence of or temperature variations often encountered inan outdoor environment, LEDs are less likely to fail than incandescentlamps. This attribute is especially important when the lamp is utilizedin motor vehicles wherein perishable filaments of incandescent lampsfrequently break due to constant vibrational motion. Further,incandescent and fluorescent lamps are constructed with fragile glassexterior casings whose breakage compromises the operational utility ofthe lamp. In contrast, the solid state LED lamp has no filaments tobreak and is usually housed within a durable plastic casing, therebyexhibiting a high level of imperviousness to extreme outdoorenvironmental stresses. A further advantage of LEDs is that they have amore rapid turn-on time and generate less heat per lumen of lightrelative to conventional lighting products. The compact size andflexibility of form of LEDs offer still further advantages in relaxingspace constraints and providing freedom to the designer to adopt newstyling configurations, such as may be useful to create brandrecognition.

A LED is a solid-state device having a PN junction semiconductor diodethat emits light when a current is applied. LEDs operate at relativelylow current and voltage and emit substantially less heat per lumen thanstandard halogen or high intensity discharge (HID) lamps. The LED can beeasily encapsulated in a resin material to protect the device and thusmake it durable and long lasting. The use of semiconductor LEDs solvesmany problems associated with incandescent bulbs including, but notlimited to, high entrapped heat, limited lamp longevity, frequent lampreplacement and higher current operation.

Recently, higher brightness white light LED lamps have becomeincreasingly affordable to manufacture and now present attractivesubstitutes for incandescent, halogen, and high intensity discharge(xenon discharge lamp) (HID) vehicle lamp sources. There are currentlythree methods for producing LEDs that emit white light. The first andsecond methods use a single blue, violet or UV LED die that emits asingle wavelength of radiation, either with a phosphoric coating thereonor a phosphoric layer between the encapsulant and the lens, with thephosphor converting portions of the light into longer wavelengths thatlead to the perception of white light. The third method uses independentred, blue, and green dies in the same package. When all three arepowered, white light is perceived.

Although more attractive as the illuminating source for the reasonsenumerated above, LEDs have not become the favored light source forheadlights and other lighting sources. For example, light distributioncharacteristics (particularly for low beam headlamps) of vehicleheadlamps have been standardized, requiring a horizontal line thatreduces glare on oncoming vehicles. Additionally, a minimum centerluminous intensity of 8000 cd or more in the front view facilitates adriver's far distance visibility. These requirements are not readilysatisfied using the single element reflector cup package known in theart.

Headlamps including multiple LED packages have been proposed to achievedesired levels of total brightness and/or directionality. Each LEDpackage includes a LED die plus a dedicated lead frame, reflector cup,encapsulant, and lens. The presence of multiple packages, particularlythose redundant packages required to switch directionality,substantially increases the cost of the overall headlamp assembly andconsumes significant volume, thus reducing packaging efficiency andreducing design options.

Accordingly, there is a continuing need in the art for improvedmulti-LED light source assemblies that minimize lamp package quantitiesand footprint while enabling directional switching for vehicular and/orother lighting applications.

SUMMARY

The present invention relates in one aspect to a multi-LED light sourceassembly employing a plurality of LED elements in a single package, witheach LED element capable of being switched independently of one another.At least two LEDs may be arranged in the same package assembly to focuslight in the same or different directions without changing the positionof the assembly.

In another aspect, the invention relates to a light emitting diode (LED)lamp, comprising: a reflector cup having a vertex, a focal point, aprincipal axis, an inside surface, and an open face; a first LED diedisposed within the reflector cup at a first position at the focal pointof the reflector; and at least one additional LED die disposed withinthe reflector cup at position different from the first position. Theposition different from the first position may be other than along theprincipal axis, or may be along the principal axis but not coincidentwith the focal point.

In another aspect, the invention relates to a light emitting diode (LED)package comprising: a first LED sub-assembly comprising a first LED die,a first reflector having a first principal axis, and a first lens; asecond LED sub-assembly comprising a second LED die, a second reflectorhaving a second principal axis, and a second lens; and a common leadframe, wherein the first LED sub-assembly and the second LEDsub-assembly are mounted to the common lead frame, the first LEDsub-assembly is adapted to emit a first beam in a first direction, andthe second LED sub-assembly is adapted to emit a second beam in a seconddirection that is different from the first direction. In one embodiment,each of the first LED sub-assembly and the second LED sub-assembly isindependently controlled.

In another aspect, the invention relates to a method of adjusting any ofthe intensity, color, and direction of light originating from a lightemitting diode (LED) lamp, the method including the steps of: providingmultiple LED die within a reflector cup with a first LED die disposed atthe focal point and at least one additional die at a location other thanalong the principal axis of the reflector cup; and independentlyoperating the first LED die and the at least one additional LED die.

In another aspect, the invention relates to a method of adjusting thecolor of light originating from a light emitting diode (LED) lamp, themethod comprising the steps of:

providing a reflector cup having a vertex, a focal point, a principalaxis, an inside surface, and an open face; providing a first RGB LEDwithin the reflector cup, the first RGB LED having a first red die, afirst green die, and a first blue die; providing a second RGB LED withinthe reflector cup, the second RGB LED having a second red die, a secondgreen die, and a second blue die; and independently operating at leastone of: any of the red dies, the blue dies, and the green dies.

In another aspect, any of the foregoing aspects may be combined foradditional advantage.

Other aspects, features and embodiments of the invention will be morefully apparent from the ensuing description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a conventional single element reflector cuplamp package known in the art.

FIG. 2 is a side cross-sectional schematic of a first surface mount LEDpackage according to the present invention, the package includingmultiple elements disposed under a symmetric lens.

FIG. 3 is a side cross-sectional schematic of a second surface mount LEDpackage according to the present invention, the package includingmultiple elements disposed under an asymmetric lens.

FIG. 4 is a side cross-sectional schematic of a third surface mount LEDpackage according to the present invention, the package including twolamp subassemblies mounted to a common lead frame, the subassemblieshaving non-parallel principal axes with symmetric lenses, symmetricreflectors, and die placed along the principal axis of each subassembly.

FIG. 5 is a two-dimensional illustration of beam paths generated by aconventional reflector known the in the art, the reflector including oneLED die, wherein substantially parallel light beams are reflectedparallel to the principal axis of the reflector.

FIG. 6 is a two-dimensional illustration of beam paths generated by alamp assembly according to the present invention including a reflectorand at least two LED dies, wherein light is reflected in at least twodifferent directions.

FIG. 7 is a cross-sectional schematic illustration of an alternativereflector having horizontal facets for use with a lamp assemblyaccording to the present invention.

FIG. 8 is a cross-sectional schematic illustration of anotheralternative reflector having vertical facets for use with a lampassembly according to the present invention.

FIG. 9 is a schematic illustration of another alternative reflectorhaving two partial paraboloids (the upper partial paraboloid having asmaller focal length than the lower partial paraboloid) with a commonapex for use with a lamp assembly according to the present invention.

FIG. 10 is a schematic illustration of another alternative reflectorhaving two partial paraboloids (the upper partial paraboloid having alarger focal length than the lower partial paraboloid) with having acommon apex for use with a lamp assembly according to the presentinvention.

FIG. 11 is a schematic depicting the relevant axes of a reflectorrelative to the angles of reflection.

FIG. 12A is a side cross-sectional schematic of a fourth surface mountLED package according to the present invention, the package includingtwo lamp subassemblies mounted to a common lead frame and each having asingle die, each subassembly having symmetric lenses and symmetricreflectors, with the die of the first (left) subassembly being disposedcoincident with the principal axis, and with the die of the second(right) subassembly being disposed non-coincident with the principalaxis.

FIG. 12B is a side cross-sectional schematic of a fifth surface mountLED package according to the present invention, the package includingmultiple die, with one die disposed coincident with principal axis ofthe subassembly and the other die disposed non-coincident with theprincipal axis.

FIG. 12C is a side cross-sectional schematic of a sixth surface mountLED package according to the present invention, the package includingtwo lamp subassemblies mounted to a common lead frame and each having asingle die, each subassembly having a symmetric lens and a die disposedalong the principal axis, with the first (left) subassembly having asymmetric reflector and the second (right) subassembly having anasymmetric reflector.

FIG. 12D is a side cross-sectional schematic of a seventh surface mountLED package according to the present invention, the package includingmultiple die, a symmetric lens, and an asymmetric reflector, with bothdie being non-coincident with the principal axis but symmetricallyarranged equidistantly from the principal axis.

FIG. 12E is a side cross-sectional schematic of a eighth surface mountLED package according to the present invention, the package includingtwo lamp subassemblies mounted to a common lead frame and each having asingle die and a symmetric lens, with the first (left) subassemblyhaving a symmetric reflector and a die disposed coincident with theprincipal axis, and with the second (right) subassembly having anasymmetric reflector and a die disposed non-coincident with theprincipal axis.

FIG. 12F is a side cross-sectional schematic of a ninth surface mountLED package according to the present invention, the package includingmultiple die, a symmetric lens, and an asymmetric reflector, with onedie disposed coincident with the principal axis and the other diedisposed non-coincident with the principal axis.

FIG. 12G is a side cross-sectional schematic of a tenth surface mountLED package according to the present invention, the package includingtwo lamp subassemblies mounted to a common lead frame and each having asymmetric reflector and a die disposed coincident with the principalaxis, the first (left) subassembly having a symmetric lens and thesecond (right) subassembly having an asymmetric lens.

FIG. 12H is a side cross-sectional schematic of an eleventh surfacemount LED package according to the present invention, the packageincluding multiple die, a symmetric reflector, and an asymmetric lens,with both die being non-coincident with the principal axis butsymmetrically arranged equidistantly from the principal axis.

FIG. 12I is a side cross-sectional schematic of a twelfth surface mountLED package according to the present invention, the package includingtwo lamp subassemblies mounted to a common lead frame and each having asymmetric reflector, the first (left) subassembly having a symmetriclens and a die disposed coincident with the principal axis, and thesecond (right) subassembly having an asymmetric lens and a die disposednon-coincident with the principal axis.

FIG. 12J is a side cross-sectional schematic of a thirteenth surfacemount LED package according to the present invention, the packageincluding multiple die, a symmetric reflector, and an asymmetric lens,with one die disposed coincident with the principal axis and the otherdie disposed non-coincident with the principal axis.

FIG. 12K is a side cross-sectional schematic of a fourteenth surfacemount LED package according to the present invention, the packageincluding two lamp subassemblies mounted to a common lead frame, eachsubassembly having a single die disposed coincident with the principalaxis, the first (left) subassembly having a symmetric lens and symmetricreflector, and the second (right) subassembly having an asymmetric lensand an asymmetric reflector.

FIG. 12L is a side cross-sectional schematic of a fifteenth surfacemount LED package according to the present invention, the packageincluding multiple die, an asymmetric reflector, and an asymmetric lens,with both die being disposed non-coincident with the principal axis butsymmetrically arranged equidistantly from the principal axis.

FIG. 12M is a side cross-sectional schematic of a sixteenth surfacemount LED package according to the present invention, the packageincluding two lamp subassemblies mounted to a common lead frame, withthe first (left) subassembly having a symmetric lens, symmetricreflector, and a die disposed coincident with the principal axis, andwith the second (right) subassembly having an asymmetric lens, anasymmetric reflector, and a die disposed non-coincident with theprincipal axis.

FIG. 12N is a side cross-sectional schematic of a seventeenth surfacemount LED package according to the present invention, the packageincluding multiple die, an asymmetric reflector, and an asymmetric lens,with one die disposed coincident with the principal axis and the otherdie disposed non-coincident with the principal axis.

DETAILED DESCRIPTION

The present invention relates to an LED light source assembly and methodof using same, and vehicular and/or portable lighting productsincorporating such assemblies. The inventive LED light source assemblyis ideally suited as a source of illumination for light sources of thetype employing reflective surfaces to produce one or more beams oflight.

Automobiles typically employ headlamps capable of operating in twomodes: (1) low beam mode, wherein light typically of a first intensityis directed in a first pattern ahead of the vehicle and down toward theroad surface to avoid dazzling drivers of opposing vehicles; and (2)high beam mode, wherein light typically of a second, higher intensity isdirected in a second pattern ahead of the vehicle and slightly upward toprovide greater forward visibility in low-light and typicallylow-traffic areas having fewer or no opposing vehicles.

A simple method for generating distinct low beam and high beam patternsis to provide separate high beam and low beam lamps each aimeddifferently. A dedicated low beam lamp is activated to generate the lowbeam pattern, and a dedicated high beam lamp is activated to generatethe high beam pattern.

Another method for generating distinct low and high beam patterns is toprovide two light sources with a shared reflector. One light source isused for the low beam mode, and the other light source is used for thehigh beam mode, with each light source positioned differently relativeto the shared reflector. To switch from low to high beam operation, aswitch is toggled to activate the high beam light source.

It is also desirable to periodically operate automotive headlamps atlevels below those of ordinary low beam mode to serve as daytime runninglights (DRLs). DRL operation is conventionally achieved with dedicatedlow wattage incandescent bulbs disposed in high or low beam headlamps,or by operating incandescent high beam headlamps at substantiallyreduced output (e.g., with a pulsed input signal).

In either low or high beam mode, entire headlamp assemblies may berepositioned utilizing conventional technologies. For example, certainautomakers (e.g., Lexus) have recently implemented headlamp assemblieswith reflectors that mechanically (automatically) adjust from side toside with steering inputs to enhance illumination while cornering.Additionally certain automakers (e.g., BMW) provide high intensitydischarge headlamp assemblies that are linked to level sensors and areservo-actuated to “dip” the reflector downward automatically if theautomobile pitches upward so as to avoid blinding oncoming drivers withflashes of light as the vehicle so equipped crests a sharp rise in thetravel surface.

Embodiments of the present invention are directed to a common package orcommon lamp including multiple associated LED dies, with individual LEDdies preferably being switched independently from one another. In oneembodiment, multiple LED dies are provided with a common reflector in asingle lamp. In another embodiment, multiple LED dies are provided in asingle package assembly, thus utilizing a common lead frame, reflector,encapsulant, and lens. Individual LEDs within a multi-LED lamp may beactivated to adjust the intensity and/or direction of the resultinglight beam.

The provision of multiple dies per reflector and/or package assemblyprovides tangible benefits. For example, the use of multiple dies canobviate the need for discrete low and high beam headlamps—or, for thatmatter for separate left and right beams, if desired.

Lighting package assemblies can therefore be placed closer together,leading to a smaller lamp package and a more uniform light source.

In general, a LED includes a die, a lead frame, and an encapsulationmaterial (e.g., an epoxy). The LED die includes a multi-layeroptoelectronic device with one or more active (light-emitting) layersdeposited over a substrate. Active layers typically comprise III-Vnitride materials (such as GaN, AlN, InN, or alloys thereof such asAlGaN or InGaN), whether provided in pure form or as alloys, such as ofAluminum, Gallium, Indium, Arsenic, and/or Phosphorus (e.g., GaAs,AGaAs, GaPAs, etc.). Typical LED substrate materials include SiC andsapphire for III-V nitride materials, and GaAs for alloy-containingmaterials, but other substrate materials may be employed. To optimizebrightness of the LED output, the substrate is preferably selected to betransparent to the wavelength of light produced by the LED;alternatively, if the substrate is not transparent, then its thicknessis minimized to reduce absorption as much as possible. Conductivesubstrates (e.g., SiC) are preferably employed to minimize the number oflight-absorptive wire bonds and contact pads on the front surface of theLED (since insulating substrates such as sapphire require two frontsidewire bonds and corresponding metal contact pads). A LED lead frameserves to not only physically support the die but also provideelectrical and thermal conduction paths to and from the die. Theencapsulation material surrounds and protects the die, and furtherserves to disperse light emitted from the die.

FIG. 1 is a schematic of a conventional single element reflector cuplamp package 1, with the LED die 50 being symmetrically positionedwithin a reflector cup 20 disposed on a heat spreader 40. The LED die iswire-bonded 30 to a post and the entire unit is covered by a lens 10. Inthese conventional LED packages, a single wire bond connection may beprovided to the top surface of the LED die, with the electrical groundconnection being made either through the backside of the die or througha second wire (not shown) bonded to the top surface of the die (e.g.,such as may be useful if an insulating material like sapphire is usedfor substrate of the active region of the die).

In conventional LED lighting assemblies, such as shown in FIG. 1, theentire reflector cup is contained within the lens. As a result, thethermal conductivity of the package is very low, since the smallelectrical lead posts are also the only viable thermal conductionpathways. This package is therefore of limited use for high brightness(and high power) LED dies.

In contrast, FIG. 2 illustrates a surface mount package 101 withmultiple elements according to one embodiment of the present invention.Surface mount packages are preferred due to the thermal requirements ofhigh-power LEDs. Instead of relying upon two small electrical lead poststo conduct heat away from the die, a large, electrically isolatedsection of the lead frame is used as a thermal pathway. Despite thespecific representation of FIG. 2, it is to be understood that varioustypes of surface mounting technologies may be used, and that theparticular illustrated configuration is not intended to be limiting inthis regard. One or more wire bonds may be provided at the top surfaceto serve as electrical connections. Vias through the LED die may also beused to conduct electricity to the top surface. Flip-chip mounts may beused; in such an instance, the back free surface of the substrate may befaceted or omitted entirely to enhance light extraction if desired.

In FIG. 2, LED-A 110 and LED-B 112 are both positioned on a heatspreader 108, which itself is positioned within a reflector cup 104. ALED-A wire-bond 106 and a LED-B wire-bond 118 are positioned to contactthe LED dies 110, 112 to adjacent posts. The entire double LED unit isencapsulated with an encapsulant 102 within the reflector cup 104 undera (symmetric) lens 100 and positioned upon a lead frame 116 containingboth electrical and thermal contacts and conduction paths. Twoalternative phosphoric layers (i.e., coating 114 and layer 120) areprovided for illustrative purposes only; depending on the method used togenerate LED light, both would not be provided in combination, andneither coating is required in certain systems.

As discussed herein, to date, white light LEDs include either (i) asingle blue, violet or UV LED die that emits a single wavelength ofradiation, the LED die including a phosphor coating that convertsportions of the light into longer wavelengths, (ii) a single blue,violet or UV LED die that emits a single wavelength of radiation, theLED lamp having an associated phosphoric layer disposed between theencapsulant and the lens, or (iii) independent red, blue and green diesin the same package that in combination create the perception of whitelight when all three are powered.

Specific implementations of the inventive surface mount LED packagehaving multiple LED sources that can be switched independently (e.g., toemit light in multiple directions) depend upon which of theabove-mentioned three methods are used for generating white light, asdiscussed in further detail below.

Surface mount packages including white light LEDs that each have asingle blue, violet or UV LED die for emitting a single wavelength ofradiation therefrom, with a phosphoric coating (e.g., coating 114 overLED-A 110 and LED-B 112 in FIG. 2) on the LED die itself (i.e., andlacking any coating 120 between the encapsulant 102 and the lens 100),may be characterized by at least one of the following arrangements:

-   -   (A) LED-A has a first reflector cup/lens/first single die        assembly and LED-B has a second reflector cup/lens/second single        die assembly, wherein LED-A and LED-B are positioned to contact        the same lead frame and wherein the first single die assembly is        oriented at a different angle relative to the second single die        assembly; (see FIG. 4, which illustrates such a package 191);    -   (B) within a single reflector cup, LED-A is positioned at the        focus of the assembly while LED-B is positioned at a location        other than the focus;    -   (C) two die are positioned within a single symmetric reflector        cup having an asymmetric lens to direct the light from one die        away from that of the second die; (see FIG. 3, which illustrates        such a package 131)    -   (D) two die are positioned within a single asymmetric reflector        cup having a symmetric lens to direct the light from one die        away from that of the second die;    -   (E) two die are positioned within a single asymmetric reflector        cup having an asymmetric lens to direct the light from one die        away from that of the second die; and    -   (F) combinations thereof.

Surface mount packages including white light LEDs that each have asingle blue, violet or UV LED die for emitting a single wavelength ofradiation therefrom, with a phosphoric layer (e.g., layer 120 in FIG. 2)located between encapsulant 102 and the lens 100 (see FIG. 2), may becharacterized by a first LED (e.g., LED-A) having a first reflectorcup/lens/first single die assembly and a second LED (e.g., LED-B) havinga second reflector cup/lens/second single die assembly, wherein thefirst and second LEDs are positioned to contact the same lead frame, andwherein the first single die assembly is oriented at a different anglerelative to the second single die assembly.

Surface mount packages including white light LEDs which includeindependent red, green and blue (RGB) die in the same package to createthe perception of white light (and therefore not requiring anyphosphoric coating 114 or phosphor layer 120 as illustrated in FIG. 2),may be characterized by at least one of the following arrangements:

-   -   (A) a first LED (e.g., LED-A) has a first reflector        cup/lens/first RGB die assembly and a second LED (e.g., LED-B)        has a second reflector cup/lens/second RGB die assembly, wherein        LED-A and LED-B are positioned to contact the same lead frame        and wherein the first single die assembly is oriented at a        different angle relative to the second single die assembly;    -   (B) within a single reflector cup, RGB LED-A is positioned at        the focus of the assembly while RGB LED-B is positioned at a        location other than the focus;    -   (C) two RGB die are positioned within a single symmetric        reflector cup having an asymmetric lens to direct the light from        one die away from that of the second die;    -   (D) two RGB die are positioned within a single asymmetric        reflector cup having a symmetric lens to direct the light from        one die away from that of the second die;    -   (E) two RGB die are positioned within a single asymmetric        reflector cup having an asymmetric lens to direct the light from        one die away from that of the second die; and    -   (F) combinations thereof.

It is contemplated that the foregoing embodiments may be incorporatedinto alternative packaging apparatuses, including reflector cup lamppackages known in the art (e.g., such as illustrated in FIG. 1, butincluding at least one another die), as well as conventional panelmount, PC mount, Sidelooker, and Subminiature package types.

FIG. 3 illustrates a multi-element LED package 131 substantiallyidentical to the package 101 depicted in FIG. 2, but the package of 131includes an asymmetric lens 100. In FIG. 3, LED-A 140 and LED-B 142 areboth positioned on a heat spreader 138, which itself is positionedwithin a reflector cup 134. A LED-A wire-bond 136 and a LED-B wire-bond148 are positioned to contact the LED dies 140, 142 to adjacent posts.The entire double LED unit is encapsulated with an encapsulant 132within the reflector cup 134 under an asymmetric lens 130 and positionedupon a lead frame 146 containing both electrical and thermal contactsand conduction paths. Two alternative phosphoric layers (i.e., coating144 and layer 150) are provided for illustrative purposes only;depending on the method used to generate LED light, both would not beprovided in combination, and neither coating is required in certainsystems.

FIG. 4 illustrates a surface mount LED package 191 according to thepresent invention, the package 191 including two lamp subassemblies 192,193 having non-coincident and non-parallel principal axes 179A, 179Bseparated by an angle “A” and being mounted to a common lead frame 176having electrical and thermal contacts, and conduction paths. While onlytwo lamp subassemblies 192, 193 are depicted in FIG. 4, it is to beunderstood that any desirable number of lamp subassemblies may bemounted along various principal axes to a common lead frame 176. Eachlamp subassembly 192, 193 may be independently operated to provide thedesired light intensity, direction, and/or color. The lead frame 176 maybe further mounted on or otherwise supported by a substrate 177. Eachsubassembly 192, 193 is illustrated as having a single LED die 170A,170B, but could alternatively include multiple LED die as illustratedand described in connection with the packages of FIGS. 2-3. Each lampsubassembly 192, 193 includes a heat spreader 168A, 168B disposed withina reflector cup 164A, 164B. Wire bonds 166A, 166B are provided toprovide electrical contact between the LED dies 170A, 170B and adjacentposts. Each LED die 170A, 170B is encapsulated with an encapsulant 162A,162B with the respective reflector cup 164A, 164B under a lens 160A,160B. A common encapsulant and common lens may be used for multiple LEDdie. Phosphoric layers of alternative types (i.e., coatings 174A, 174Band layers 180A, 180B) may further be provided.

In embodiments according to the present invention, the entire reflectorlamp is preferably manufactured as a complete light package, wherein theLED dies are protected from the elements by an enclosedencapsulant/reflector/lens covering combination.

Reflector cup shapes contemplated herein, of types both symmetric andasymmetric, are illustrated in FIGS. 5-10, as discussed below. It is tobe understood that the dimensions and shape of the reflector cups aremerely illustrative, and are not intended to limit the dimensions orshapes of reflector cups that may be used with device according to thepresent invention.

FIG. 5 illustrates a simple reflector headlamp 210 having a single die212 positioned at the focal point 214 of a paraboloidal reflectorsurface 216. As is well known to those skilled in the art, lightoriginating from the focal point will travel parallel to the principalaxis 218 after reflection off of the paraboloid surface, as illustratedschematically in FIG. 1 by the arrows 220. Although not illustrated inFIG. 1, the headlamp may further include a symmetric or asymmetric lenswhich may have additional patterns to direct the reflected light beam inpreferred directions.

FIG. 6 illustrates another embodiment of the present invention includinga reflector headlamp 310 having a first die 312 positioned at the focalpoint 314 of the reflector surface 316, whereby light originating fromthe focal point will travel parallel to the principal axis 318 followingreflection off of the reflector surface, as illustrated schematically inFIG. 6 by the arrows 320. In addition, the reflector headlamp 310includes a second die 322 that is positioned at some location other thanalong the principal axis 318. In the embodiment illustrated in FIG. 6,the second die 322 is positioned below the first die 312 along animaginary axis 326 that runs perpendicular to the principal axis 318 atthe focal point 314 of the first die. In practice, the second die 322may be above the first die and/or positioned anywhere along theprincipal axis at some angle relative to the focal point 314, but not onthe principal axis (for example all angles relative to the focal pointexcluding 0° and 180°). As a further alternative embodiment, a reflectorheadlamp according to the present invention may include more than twoLED dies in the same headlamp assembly (e.g., one die at the focal pointand one die each above and below the principal axis, etc.). As yetanother alternative, neither of the at least two LED dies are positionedat the focal point. As a still further alternative, one of the at leasttwo LED dies is positioned at the focal point, while the other at leastone die is positioned along the principal axis but not at the focalpoint.

Most of the light originating from the second die 322 will not travelparallel to the principal axis 318 subsequent to reflection off of thereflector. Instead, the reflected light (324, represented by dottedlines in FIG. 6) originating from the second die 322 will travel atvarious angles relative to the principal axis because the position ofthe second die 322 does not correspond to a focus of the reflector. In aparticularly preferred embodiment, wherein the second die 322 ispositioned below the principal axis 318, a substantial portion of thereflected light 324 from the second die 322 will travel at angles 270°to 360° relative to the principal axis, whereby angles 270° to 360°relative to the principal axis is illustrated in FIG. 11 for ease ofreference. In other words, if the second die 322 is closer to the groundthan the first die 312, a substantial portion of the reflected lightfrom the second die 322 will be pointed upwards from the ground at avariety of angles. Analogously, when the second die 322 is positionedabove the principal axis 318, a substantial portion of the reflectedlight from the second die 322 will travel at angles 0° to 90° relativeto the principal axis (see FIG. 11). As defined herein, a “substantialportion of the reflected light” relative to a particular angular rangecorresponds to greater than 50% of the total amount of reflected lighttravels in the angular range, more preferably greater than 70% of thetotal amount of reflected light, and still more preferably greater than80% of the total amount of reflected light.

It is contemplated herein that the shape of the reflector may be anyshape that will reflect light originating from a plurality of LED diesin a plurality of different directions. Contemplated shapes includeparabolic shapes such as the aforementioned paraboloid, ellipsoids ofrevolution, retroreflectors, and compound curves generated by computerprograms. Although illustrated as a smooth reflector, a furtheralternative includes the faceting of the inner surface of the reflector,for example, facets that extend generally horizontally relative to aprincipal axis, as shown in FIG. 7; that extend generally verticallyrelative to a principal axis, as shown in FIG. 8; or that extend bothhorizontally and vertically. Faceting is known to facilitate uniformityof the beam produced thereby. Similar to the reflector shown in FIG. 6,the faceted reflectors illustrated in FIGS. 7 and 8 may have two or moreLED dies, and the positioning of the two or more LED dies may correspondto those described with reference to FIG. 6. It should be appreciatedthat if the inside surface of the reflector is faceted, lightoriginating from the first die may, by design, not travel parallel tothe principal axis.

In another embodiment according to the present invention, a reflectorincludes an asymmetric reflector cup having two partial paraboloids (orany other combination of the aforementioned reflector shapes) with acommon vertex, with each paraboloid having different focal distances anda common principal axis. Examples include FIG. 9, wherein the reflector410 includes an upper partial paraboloid 412 having a smaller focallength than the lower partial paraboloid 414, and FIG. 8, wherein thereflector 510 includes an upper partial paraboloid 512 having a largerfocal length than the lower partial paraboloid 514. The positioning ofthe first die may be at the focal point of either partial paraboloid, asreadily determinable by one skilled in the art. Similar to FIGS. 7 and8, the two partial paraboloid reflectors illustrated in FIGS. 9 and 10may have faceted or smooth reflector surfaces, may have two or more LEDdies, and the positioning of the two or more LED dies may correspond tothose described with reference to FIG. 6.

Although not illustrated in FIGS. 6-10, LED headlamps according to thepresent invention may further include a symmetric or asymmetric lenswhich may or may not include additional patterns or some other secondaryoptics to direct the reflected light beam in preferred directions.Alternatively, a flat window lacking curvature and/or optical power maybe provided.

In further embodiments, various combinations of die placement, lensshape, reflector shape, and—in packages including multiplesubassemblies, subassembly placement (angular or otherwise)—may beselected to provide desired functionality. As noted previously, FIG. 4illustrates a lamp package having two lamp subassemblies mounted to acommon lead frame, with the subassemblies having non-parallel principalaxes. FIGS. 12A-12N illustrate additional lamp packages according tofurther embodiments of the invention. For the sake of simplicity,certain features such as wire bonds and phosphoric layers have beenomitted from FIGS. 12A-12N, but it is to be understood that suchfeatures are intended to be present (where appropriate) in actual LEDlamp packages constructed according to the present invention. It is tobe further understood that even though FIGS. 12A-12N depict only two dieper package and up to two subassemblies, almost any number of die andsubassemblies may be provided in any given package according to thepresent invention.

FIG. 12A illustrates a surface mount LED package 601 including two lampsubassemblies 602, 603 mounted to a common lead frame 616 and eachhaving a single die 610A, 610B. Each subassembly 602, 603 has asymmetric lens 600A, 600B disposed over an encapsulant 612A, 612B and asymmetric reflector 604A, 604B, with the die 610A of the first (left)subassembly 602 being disposed coincident with the principal axis 609Aof the subassembly 602, and with the die 610B of the second (right)subassembly 603 being disposed non-coincident with the principal axis609B of the subassembly 603.

FIG. 12B illustrates a surface mount LED package 631 having a lead frame646 and multiple dies 640, 641, with one die 641 disposed coincidentwith a principal axis 639 of the package 631 and the other die 640disposed non-coincident with the principal axis 639. The package 631further includes a symmetric lens 630 disposed over an encapsulant 642and a symmetric reflector 634.

FIG. 12C illustrates a surface mount LED package 661 including two lampsubassemblies 662, 663 mounted to a common lead frame 676 and eachhaving a single die 670A, 670B. Each subassembly 662, 663 has asymmetric lens 660A, 660B disposed over an encapsulant 672A, 672B, withthe reflector 664A of the first subassembly 662 being symmetric, and thereflector 664B of the second subassembly 663 being asymmetric. Each die670A, 670B is disposed coincident with the principal axis 669A, 669B ofits respective subassembly 662, 663.

FIG. 12D illustrates a surface mount LED package 701 having a lead frame716 and two die 710, 711 being disposed non-coincident with theprincipal axis 709 but symmetrically arranged equidistantly from theprincipal axis 709. The package 701 further includes a symmetric lens700 disposed over an encapsulant 712 and an asymmetric reflector 704.

FIG. 12E illustrates a surface mount LED package 731 including two lampsubassemblies 732, 733 mounted to a common lead frame 746 and eachhaving a single die 740A, 740B. Each subassembly 732, 733 has asymmetric lens 730A, 730B disposed over an encapsulant 742A, 742B, withthe reflector 734A of the first subassembly 732 being symmetric, and thereflector 734B of the second subassembly 733 being asymmetric. In thefirst subassembly 732, the die 740A is disposed coincident with theprincipal axis 739A, and in the second subassembly 733, the die 740B isdisposed non-coincident with the principal axis 739B.

FIG. 12F illustrates a surface mount LED package 761 having a lead frame776 and two die 770, 771, with one die 771 disposed coincident with theprincipal axis 769 and the other die 770 disposed non-coincident withthe principal axis 769. The package 761 further includes a symmetriclens 760 disposed over an encapsulant 772 and an asymmetric reflector764.

FIG. 12G illustrates a surface mount LED package 801 including two lampsubassemblies 802, 803 mounted to a common lead frame 816 and eachhaving a single die 810A, 810B. The first subassembly 802 has asymmetric lens 800A and the second subassembly 803 has an asymmetriclens 800B. Each lens 800A, 800B is disposed over an encapsulant 812A,812B and a symmetric reflector 804A, 804B, with each die 810A, 810Bbeing disposed coincident with the principal axis 809A, 809B of itsrespective subassembly 802, 803.

FIG. 12H illustrates a surface mount LED package 831 having a lead frame846 and two die 840, 841 The package 831 further includes an asymmetriclens 830 disposed over an encapsulant 842 and a symmetric reflector 834.

FIG. 12I illustrates a surface mount LED package 861 including two lampsubassemblies 862, 863 mounted to a common lead frame 876 and eachhaving a single die 870A, 870B. The first subassembly 862 has asymmetric lens 860A, and the second subassembly 863 has an asymmetriclens 860B. Each lens 860A, 860B is disposed over an encapsulant 872A,872B and a symmetric reflector 864A, 864B. The first die 870A isdisposed coincident with the principal axis 869A of the firstsubassembly 862, and the second die 870B is disposed non-coincident withthe principal axis 869B of the second subassembly 863.

FIG. 12J illustrates a surface mount LED package 901 having a lead frame916 and two die 910, 911, with one die 911 being disposed coincidentwith the principal axis 909 and the other die 910 being disposednon-coincident with the principal axis 909. The package 901 furtherincludes an asymmetric lens 900 disposed over an encapsulant 912 and asymmetric reflector 904.

FIG. 12K illustrates a surface mount LED package 931 including two lampsubassemblies 932, 933 mounted to a common lead frame 946 and eachhaving a single die 940A, 940B disposed coincident with the respectiveprincipal axis 939A, 939B. The first subassembly 932 has a symmetriclens 930A, and the second subassembly has an asymmetric lens 930B. Eachlens 930A, 930B is disposed over an encapsulant 942A, 942B, with thereflector 934A of the first subassembly 932 being symmetric, and thereflector 934B of the second subassembly 933 being asymmetric.

FIG. 12L illustrates a surface mount LED package 961 having a lead frame976 and two die 970, 971 being disposed non-coincident with theprincipal axis 969 but symmetrically arranged equidistantly from theprincipal axis 969. The package 961 further includes an asymmetric lens960 disposed over an encapsulant 972 and an asymmetric reflector 964.

FIG. 12M illustrates a surface mount LED package 1001 including two lampsubassemblies 1002, 1003 mounted to a common lead frame 1016 and eachhaving a single die 1010A, 10108. The first die 1010A is disposedcoincident with the principal axis 1009A of the first subassembly 1002,and the second die 10108 is disposed non-coincident with the principalaxis 1009B of the second subassembly 1003. The first subassembly 1002has a symmetric lens 1000A, and the second subassembly has an asymmetriclens 1000B. Each lens 1000A, 1000B is disposed over an encapsulant1012A, 1012B, with the reflector 1004A of the first subassembly 1002being symmetric, and the reflector 1004B of the second subassembly 1003being asymmetric.

FIG. 12N illustrates a surface mount LED package 1031 having a leadframe 1046 and two die 1040, 1041. One die 1041 is disposed coincidentwith the principal axis 1039 and the other die 1040 is disposednon-coincident with the principal axis 1039. The package 1031 furtherincludes an asymmetric lens 1030 disposed over an encapsulant 1042 andan asymmetric reflector 1034.

Certain embodiments of the present invention correspond to a single lamppackage having two or more light emitting regions with the intent offocusing or otherwise directing the light in two or more differentdirections, wherein one light emitting region can be switchedindependently of a second light emitting region. Properly oriented, alamp package according to the present invention may be used in aheadlight assembly to transition between low beam and high beamoperation. For example, low beam operation may correspond to thereflected light originating from the second die, while high beamoperation may correspond to the reflected light originating from thefirst die. Alternatively, low beam operation may correspond to thereflected light originating from one of the LED dies, while high beamoperation may correspond to the reflected light from the at least twoLED dies. Other combinations are contemplated and readily determinableby one skilled in the art.

In various specific embodiments of the invention, such as thoseillustratively mentioned above, the spectral output of the each die in amulti-die LED device or package may be white light. For example, amulti-die LED device or package having white light spectral output fromeach die or combinations of die may be used to provide both high beamand low beam output, preferably with differing intensity and directionof the low and high beams, respectively. In other embodiments, thespectral output of the light emission device may be light having aspecific color other than white light as dictated by the color of thetwo or more LED dies chosen. In a LED employing RGB dies, the color ofthe light output may also be controlled by the relative amount of red,blue, and green light provided by the individual dies. For example, afirst die having white light spectral output may be used for forward(e.g., high and/or low beams) or rearward illumination (e.g., backuplights), and a second yellow die may be utilized for turn signalingutility; or, alternatively, a second red die may be used to indicateapplication of brakes (i.e., brake lights). In still furtherembodiments, the spectral output of the light emission device mayinclude output that is outside the visible radiation spectrum. Forexample, a first die having white light spectral output may be used forvisible forward illumination, while a second die having infrared outputmay be used as part of a night vision enhancement system. In such anembodiment, an infrared beam bathes the road ahead and forward objectsin infrared light, a car-mounted forward infrared camera is used todetect objects beyond the reach of the while light beam (e.g., low orhigh beam lamps), and a display device such as a car-mounted monitor orwindshield projector is used to alert the driver to the presence ofotherwise imperceptible forward objects. Such an enhanced night visionsystem is particularly useful in vehicles traveling at night at highrates of speed.

In another embodiment, a lamp is communicatively connected to aphoto-sensor capable of imaging the road ahead. If the photo sensorsenses that no other automotive lights are present, whether oncoming ortraveling ahead in the same direction, the system automatically changesto high beam operation. When traffic is sensed by the photo-sensor, thesystem automatically changes to low beam operation.

In yet another embodiment, a reflector headlamp includes more than twoLED dies to serve as directional headlamps that may be used to enhancelighting while the vehicle is cornering.

The arrangement of the LED dies within the reflector is readilydeterminable by one skilled in the art upon review of the presentdisclosure. As indicated previously, surface mount LED packages arepreferably used to accommodate the thermal requirements of high-powerLEDs. For example, “flip-chip” LED dies with all of the contacts on thebottom surfaces thereof may be employed to advantageously reducelight-blocking problems associated with electrical contacts disposedatop dies, to which electrical wire may be bonded.

To control the amount of light emitted by multiple LED dies, currentand/or voltage can be sourced individually to each die, if theassociated cost and complexity of wiring and power supply arrangementsis suitable for the intended end use application. In one embodiment,multiple LED lamps are mounted to a common electrical distributionelement such as printed circuit board. In this manner, power can bedistributed to a multitude of lamps with a relatively small number ofelectrical connections to a power source, with appropriate switching andcontrol functions provided by a microprocessor integrated to the circuitboard. For example, with multiple LED lamps mounted to a single circuitboard, a single wiring harness may be utilized to connect the lamps tothe electrical system of a motor vehicle. Alternatively, light output ofthe light emission device can be controlled by variation in diefabrication, die shape, die size (area), contact quality, overallstructure resistance, or the like, or by altering other aspects of theLED design.

Embodiments of the present invention providing a single LED lamp havingtwo or more light emitting regions may be used for vehicular and/orportable lighting products including, but not limited to, flashlights,lanterns, portable work lights, spotlights, headlights, brake lights,tail lights, turn signal lights, daytime running lights, traffic lights,penlights, recessed lighting, dashboard lighting, or other similarapplications.

While the invention has been described herein with reference to specificaspects, features and embodiments, it will be recognized that theinvention is not thus limited, but rather extends to and encompassesother variations, modifications and alternative embodiments.Accordingly, the invention is intended to be broadly interpreted andconstrued to encompass all such other variations, modifications, andalternative embodiments, as being within the scope and spirit of theinvention as hereinafter claimed.

What is claimed is:
 1. A light emitting diode (LED) lamp, comprising: anasymmetric lens; an array of LEDs mounted on or over a common submount,wherein emissions of the array of LEDs are arranged to be transmittedthrough the lens, and wherein a center of the array of LEDs is offsetrelative to a center of the lens.
 2. The LED lamp of claim 1, whereinthe array of LEDs are disposed within a reflector cup.
 3. The LED lampof claim 2, wherein the reflector cup is asymmetric.
 4. The LED lamp ofclaim 2, wherein the reflector cup is mounted on or over the submount.5. The LED lamp of claim 1, wherein the submount comprises a lead frame.6. The LED lamp of claim 1, wherein the submount comprises a printedcircuit board.
 7. The LED lamp of claim 1, wherein each LED of the arrayof LEDs comprises a surface mount LED.
 8. The LED lamp of claim 1,further comprising at least one phosphor material layer arranged betweenthe array of LEDs and the lens, wherein the at least one phosphormaterial is remotely located relative to each LED of the array of LEDs.9. The LED lamp of claim 1, wherein each LED of the array of LEDs isarranged non-coincident with a vertex of the LED lamp.
 10. The LED lampof claim 1, wherein each LED of the array of LEDs is arranged to outputwhite light.
 11. The LED lamp of claim 1, wherein the array of LEDscomprises at least one LED arranged to output red light or infraredlight.
 12. The LED lamp of claim 1, comprising a photosensor, whereinoperation of the LED lamp is controlled responsive to an output of thephotosensor.
 13. The LED lamp of claim 1, comprising a plurality of LEDpackages.
 14. The LED lamp of claim 1, arranged to illuminate a roadway.15. A method for illuminating a surface or roadway utilizing a LED lampaccording to claim 1, the method comprising supplying electric power tothe array of LEDs.